Networking / PTP
PTP clock sync problems on a Dante or AES67 network
PTP (Precision Time Protocol) is the heartbeat of an AV-over-IP network. When it's unstable, you get clicks, dropouts, and devices flapping. Most PTP problems come down to who's the grandmaster and whether the switch fabric is handling PTP correctly.
1. Identify the current grandmaster
Exactly one clock should be the grandmaster for the network. Use Dante Controller's clock status (or your DSP's PTP view) to see which device is leader. If it changes frequently, you have an election problem — the network keeps re-choosing a clock.
2. Set a deliberate clock leader
- 1Don't leave clock leadership to chance. Designate a stable, always-on device (often the primary DSP/core) as preferred leader.
- 2Disable 'preferred leader' on transient devices like laptops or portable I/O that come and go.
- 3Confirm the chosen leader has a clean, low-jitter view of the network.
3. Check the switch for PTP-hostile settings
Energy-efficient Ethernet (EEE / green Ethernet) is a common PTP killer — disable it on all AV ports. Also confirm the switch either passes PTP transparently or acts as a proper boundary clock; a switch that mangles PTP timestamps introduces jitter that shows up as audio artifacts.
4. Watch for two clock domains bridging
If two separate audio networks get accidentally bridged (a patched cable, a trunk misconfig), their grandmasters fight and both networks destabilize. Isolate segments and verify only one clock domain exists per audio VLAN.
Frequently asked
What are the symptoms of bad PTP?
Periodic clicks/pops, brief dropouts across multiple devices at once, and devices repeatedly re-syncing. If many devices glitch together, suspect the clock.
Does EEE really cause PTP problems?
Yes — Energy-Efficient Ethernet introduces latency as ports sleep/wake, corrupting PTP timing. Disable it on every AV switch port.